Piezoelectric actuator with a new type of contacting and a method for the production thereof

Abstract

A piezoelectric actuator, and method of producing same, wherein electrically conductive contact tabs are applied onto metallization strips in such a way that a projecting region remains, so that in the event of cracks nevertheless occurring, such cracks run in the projecting region of the contact tab and are bridged electrically.

What is claimed is:  
     
       1. A piezoelectric actuator, comprising: 
       a plurality of piezoelectric ceramic layers;  
       a plurality of electrode layers alternately arranged with the plurality of piezoelectric ceramic layers, one above another, to form a stack;  
       at least two metallization strips applied to sides of the stack, wherein the electrode layers are alternately connected with alternating polarity to the at least two metallization strips; and  
       at least two contact tabs, each of the at least two contact tabs having an electrically conductive layer with a first portion connected to one of the at least two metallization strips over an entire height of the respectively connected electrode layers, each of the at least two contact tabs includes a projecting region extending from said first portion at a side of the respective metallization strip, said projecting region being a flag-like projection free of said metallization strip and free of said stack.  
     
     
       2. A piezoelectric actuator as claimed in claim  1 , wherein the piezoelectric actuator is of a monolithic construction. 
     
     
       3. A piezoelectric actuator as claimed in claim  1 , wherein each of the at least two contact tabs is formed of both an electrically conductive layer and a plastic layer. 
     
     
       4. A piezoelectric actuator as claimed in claim  3 , wherein each of the at least two contact tabs is a metal-coated plastic film. 
     
     
       5. A piezoelectric actuator as claimed in claim  1 , wherein the projecting region extends outward from the associated metallization strip at least 5 mm. 
     
     
       6. A piezoelectric actuator as claimed in claim  1 , wherein each of the at least two contact tabs is formed of an electrically conductive layer and, in a region extending away from the associated metallization strip, is laminated with plastic on both sides and, in a region which connects to the associated metallization strip, is at most laminated with plastic on one side. 
     
     
       7. A piezoelectric actuator as claimed in claim  1 , wherein each of the at least two contact tabs is formed of a plastic film coated with copper. 
     
     
       8. A piezoelectric actuator as claimed in claim  1 , wherein each of the at least two metallization strips has a baked metallization composition. 
     
     
       9. A method for producing a piezoelectric actuator, comprising the steps of: 
       arranging a plurality of piezoelectric ceramic layers alternately with a plurality of electrode layers one above another to form a monolithic composite stack;  
       applying at least two metallization strips at sides of the stack;  
       connecting, alternately, the plurality of electrode layers with alternating polarity to the at least two metallization strips;  
       providing at least two contact tabs, wherein each contact tab has an electrically conductive layer; and  
       connecting the electrically conductive layer of a portion of each of the at least two contact tabs to one of the at least two metallization strips over an entire height of the respectively connected electrode layers, a projecting region of each of the at least two contact tabs extends from said portion and remains free of contact with said metallization strips at a side of the respective metallization strip.  
     
     
       10. A method of producing a piezoelectric actuator as claimed in claim  9 , further comprising the steps of: 
       forming a solder layer on the electrically conductive layer of each of the at least two contact tabs in a region to be connected to the associated metallization strip; and  
       soldering the contact tab to the associated metallization strip.  
     
     
       11. A method of producing a piezoelectric actuator as claimed in claim  10 , wherein the step of soldering is performed via laser soldering.